All About Building a Guest House or Guest Living Quarters

Building a guest house can be a great way to increase your property’s value or provide additional living space for family and guests. Whether you’re considering a small one bedroom unit or a large 1,200 square foot space, understanding the costs, design options, and regulations involved is essential. This guide will walk you through everything you need to know about planning, financing, and constructing a guest house in your backyard plus explore the differences between a guest house and guest living quarters.

What Is a Guest House?

A guest house is a secondary living space on a property that provides accommodation for guests, family members, or tenants. They are primarily detached, standalone units, but they can also be attached to the primary home or a conversion of existing space such as a garage.

What Is the Difference Between a Guest House and an ADU?

Many people use the terms “guest house” and “Accessory Dwelling Unit (ADU)” interchangeably. Many times someone will refer to an ADU as a guest house when the unit is used as a flexible space for overnight guests, a home office, a pool house, etc. However, many cities around San Diego have separate regulations for a term called “guest quarters”, which are completely different.

What Is the Difference Between a Guest House and Guest Living Quarters?

Guest living quarters (referred to as just guest quarters in some jurisdictions) differ from guest houses and ADUs, and definitions vary by jurisdiction.

For example, San Diego County says that guest living quarters cannot include full kitchens, laundry facilities, or wet bars and are restricted to temporary use. Guest quarters in the city of San Diego may include a bar sink and mini-fridge but cannot have full kitchen facilities.

Some jurisdictions do not allow guest living quarters at all or have mention of them in their code, and some jurisdiction such as Encinitas and Carlsbad refer to “guest quarters” as a “guest house”. This can add a layer of confusion since many people refer to ADUs as guest houses. Understanding your local rules is crucial to ensuring your guest house and/or guest quarters project complies with local regulations.

Can I Build a Guest House in my Backyard or on My Property? 

Many homeowners ask, “Can I build a guest house in my backyard?” In most instances, the answer in California is yes. California state laws allow for an 800 square foot detached guest house (ADU) on any single-family property, with a 16 foot height limitation and 4 foot setbacks from property lines. Local regulations may permit larger units.

What Determines Whether You Can Build a Guest House?

Per California state law if you have the space to meet setback requirements, you are allowed by right to build an ADU of at least 800 square feet. Cities and counties may have additional regulations concerning setbacks, height restrictions, and whether multi-story guest houses are allowed. It’s essential to check your local zoning laws and consult with an experienced guest house builder to determine what’s possible for your property. If you are unsure as to whether you can build a guest house, we recommend reaching out to our team!

Guest House Size Limits in San Diego County and Cities

Guest houses must meet minimum habitable space requirements of at least 150 square feet, while maximum sizes are set by state law and local jurisdictions. In most jurisdictions, you can build up to 1,200 square feet. However, there are a few jurisdictions such as San Marcos and Coronado that only allow up to 1000 square feet. Poway on the other hand allows up to 1500 square feet in certain cases. Check out our regulations page to see the size limit in your jurisdiction.

Guest House Requirements in California and San Diego

Zoning Requirements

Guest houses are permitted on single family and multifamily zoned properties but are generally not allowed in commercial or industrial zones. Depending on your zoning you may be able to build multiple guest houses. For instance, you can build more guest houses if you have a multifamily zoned property.

Setback and Height Requirements

California state law allows for a maximum of 16 feet in height for a statewide exemption guest house. If the property is within a half mile of a major public transit stop, the height limit is increased to 18 feet. Many jurisdictions allow heights beyond this depending on the zone. Most jurisdictions require a setback of four feet from the property line, and a six to ten foot set back from existing structures. Fronts and backs are determined by zoning. There are some outliers, so it’s important to check your specific jurisdictions regulations.

Lot Coverage Limits

Lot coverage limits determined by zoning cannot prevent you from building an 800 square foot guesthouse. If you would like to build a guest house bigger than 800 square feet, then you must abide by floor area ratio (FAR) and lot coverage requirements.

Parking Requirements

In many instances, parking is not a requirement for a guest house. If your property is within a half mile of public transit (including a bus stop), within an established historic district, or converted from existing space, then parking is not required.

Utility & Permit Requirements

Building permits are required to construct a guest house. Depending on the project utility upgrades may be needed such as an electrical panel upgrade or sewer lateral upgrade. Separate metering can be required.

The Benefits of Building a Guest House

Financial Benefits of a Guest House

Building a guest house can significantly increase property value. It provides additional livable square footage, which can boost resale value. If used as a rental, a guest house can generate passive income. Many properties with ADUs or guest houses sell at a premium because they offer income producing potential. Read more about renting your guest house.

Lifestyle Benefits of a Guest House

A guest house isn’t just an investment, but also a highly functional addition to your home. Some common use cases include:

• Hosting guests – Provide comfortable accommodations for family and friends. For example, check out this Flex Space ADU in San Diego designed to be used either as additional accommodations for the homeowner’s family or as a rental.
• Multigenerational living – Give aging parents or adult children a private, independent space. Read more about multigenerational ADUs.
• Rental income – Offset mortgage costs by renting out your guest house.
• Home office or creative studio – Create a quiet workspace away from the main house.
• Pool house or entertainment area – Enhance your backyard with a stylish and practical space. Read more about poolside ADUs and take a look at this modern pool house ADU in Carlsbad for some inspiration!

How Much Does a Guest House Cost?

Cost to Build a Guest House in San Diego

The cost of building a guest house varies greatly based on size, design, and materials as well as the property’s existing site and utility conditions. In San Diego, costs generally range from $300,000 to $500,000 all-in for a detached unit. The cost per square foot typically falls between $375 and $600 with construction accounting for about 80-85% of the total cost, while the remainder includes soft costs such as design, permits, and consultants and other site specific work and utilities. Read more about guest house costs.

Financing Options for Your Guest House

Financing a guest house can be done through various methods, including:

• Home equity loans – Borrow against your existing home equity.
• Cash-out refinancing – Refinance your mortgage to free up funds.
• Construction loans – Obtain a loan specifically for building expenses.

While SnapADU does not offer in-house financing, we work with reputable lenders to help homeowners secure funding. Read more about financing your guest home.

Building a Guest House – What to Know Before You Start

Feasibility as the First Step

A feasibility study is the first and most critical step in determining whether you can build a guest house on your property. Our analysis evaluates zoning regulations, existing site conditions, utility access, and any potential roadblocks that could impact the project. Completing a feasibility study upfront ensures that the project is financially and practically viable before moving forward with design and permitting.

Building Process

Building a guest house involves several steps, including the feasibility study, design, permitting, and construction. The entire process can take 12 to 18 months, with design taking 3 to 4 months, permitting taking 3 to 6 months, and construction taking 6 to 8 months.

Choosing a pre-approved plan or SnapADU Build Ready design can help speed up the design and permitting process and minimize delays. The most common issues that affect guest house project timelines include city permitting delays, additional approvals required for coastal zones or HOAs, utility upgrades, and plan modifications. Read more about factors that affect project timeline.

Construction Options for a Backyard Guest House

There are many ways you can approach guest house construction, and each comes with its own benefits and trade offs.

Custom Guest House Construction

Custom guest houses allow for the most flexibility in terms of layout, size, and style. They are ideal for homeowners with specific requirements like designing for accessibility or matching the primary home’s architecture. Semi-custom guest houses can also be a great option to use an existing plan and then make modifications. This option saves time and money compared to a fully custom guest house with the ability to add some personalized elements. Check out our Custom ADU Guide.

Prefabricated and Modular Guest Houses

Prefabricated or modular guesthouses are built off site and then either craned in or assembled on the property. They offer simplified design decisions and shorter construction timelines. However, they’re typically limited in customization options and still require the same site prep and permitting that stick build guest houses require. Additionally, more complex sites may not be well suited for a prefabricated guest house. Check out our Prefab ADU guide.

Converting Existing Structures into a Guest House

Garage or other structure conversions can be a cost effective option to add a guest house if the existing building is in a good condition. However, not every structure is a good candidate which is why feasibility analysis is crucial. Many of our clients have opted to demolish their older detached garage and build a guest house from scratch for this reason. Read more about conversion versus demo rebuild.

Designing a Guest House That Fits Your Property

A good guest house design balances functionality privacy and long term flexibility.

Layout and Space Planning

An efficient layout can make a small guest house feel spacious. Open floor plans, high vaulted ceilings, built-in storage, and room placement can significantly improve livability. When designing a guest house, think about the use case. For instance, if building a guest house to generate rental income, consider who your ideal tenants may be. The ideal layout for a family in Encinitas may be different than the ideal layout for college students near SDSU.

Privacy, Access, and Placement

Placement on the lot plays a big role in privacy for both the main home and the guesthouse. When designing a guest house, consider separate entrances, window placement, landscaping and fencing buffers, and how outdoor living areas will be shared or separated.

Designing for Accessibility or Future Use

When designing a guest house, it’s wise to keep future needs in mind. If an older family member is going to be living in the guest house or may be will be at some point, consider adding features such as wider doorways and zero-threshold showers for better accessibility. Even if your initial use case is for guests, designing with flexibility in mind adds long-term value.

Choosing the Right Guest House Builder

Working with Guest House Contractors

Hiring a reputable and licensed builder is crucial for ensuring a smooth construction process. A good builder will help with design, permitting, and construction while keeping the project on schedule and within budget. When choosing a builder, consider:

• Their experience with ADUs and guest houses
• Customer reviews and testimonials
• Licensing and insurance status
• Their ability to provide accurate quotes and timelines

Getting multiple quotes and checking references can help you avoid common pitfalls and ensure you select a builder who aligns with your goals. We recommend reading through our detailed blog post on choosing your guest house contractor.

Top Guest House Builders in San Diego: Why SnapADU?

At SnapADU, we specialize in designing and building guest houses throughout San Diego County. With extensive experience in designing and building over 150 ADUs, we understand the complexities involved and offer comprehensive services, including custom design, permitting, and ADU construction. Our expertise ensures that each project is completed smoothly, on time, and in compliance with all local regulations. Whether you’re building for flex space, guests, multigenerational living, or even as a rental, SnapADU delivers high quality, well designed guest houses that maximize your property’s potential!